JSC2013-E-024885 (23 April 2013) --- NASA astronaut Steve Swanson, Expedition 39 flight engineer and Expedition 40 commander, attired in a training version of his Extravehicular Mobility Unit (EMU) spacesuit, is about to be submerged in the waters of the Neutral Buoyancy Laboratory (NBL) near NASA's Johnson Space Center. Divers (out of frame) are in the water to assist Swanson in his rehearsal, which is intended to help prepare him for possible work on the exterior of the International Space Station. Photo credit: NASA